January 2, 2009

You have eight almost identical balls, but one of them is a little bit lighter than the others. It is not that lighter, though, that you can tell the difference by hand, but you have a two-armed balance. How can you find the light ball with only two measures?

3 comments:

make a group of 3,3,21. Measure group of 3,3 on the balance.case a. If two groups equal the defected ball is in group of 2. Go to step 2.case b. If one of the group3 is heavy the other group of 3 conains the defected ball.Go to Step 3.

2. Measure the two balls you will get the defected. Your work is done. STOP

3. Distribute this group into further 3 groups of 1 ball each.Measure any two balls case a. If both are equal the third ball is the culprit. STOPcase b. If not equal then Step2 folows. STOP